Earthshock (episode four, 16 March 1982)

SPOILER ALERT: We are discussing some of the Doctor Who adventures broadcast over the past 50 years. In this blog, we're looking at Earthshock. It contains spoilers both about the specific episode and the story as a whole.

I dithered over whether to include this one in our list: I'm not the biggest fan of either the Peter Davison era or the latter-period Cybermen. But the series was certainly popular – sometimes shock value works. Earthshock is a more pacy story than I remember, with episode four in particular ramping things up to breathless tension.

The Doctor, Nyssa, Tegan and Adric (yes, all of them) intercept an archaeological mission in 2516 that comes under attack from murderous androids who are guarding a bomb on a freighter in deep space. The revelation of who is behind the bomb is one of the greatest shocks in Doctor Who history.

The Cybermen had not been seen since 1975, and that appearance had been the first since the Troughton era. Producers kept their return secret, cancelling a Radio Times cover, and shutting down the studio's public gallery. Here was the No 2 villain, woken from slumber with another harebrained attack on Earth in store.

Those viewing at the time recall a genuine gasp moment. You can trace Steven Moffat's obsession with secrecy and big reveals right back to this point. But Earthshock has another sting in its tail: the shock killing of Adric. Fans argue whether unfortunates such as Sara Kingdom, Katarina and Kylie's Astrid count as full-time companions, but this was the only time a long-term companion came to a grisly end.

That event alone earns it a gilded place in the canon, and we'll go into both shortly. But there's another reason to adore Earthshock: that's tottering luvvie Beryl Reid hilariously miscast as Briggs, gruff commander of the freighter. For all its baggage, I will remember Earthshock most fondly as the one where Beryl Reid does a karate chop.

Life aboard the Tardis

With Tom Baker's avuncular weirdo on the way out, the show was retooled for the arrival of the youthful Davison, and the lead cast become a kind of Scooby Gang. Aboard this crowded Tardis were serene alien aristocrat Nyssa of Traken and argumentative Australian air hostess Tegan Jovanka. The two made for an enduring sister act, but three companions was too many, and there was no doubt who had to go: Adric, a worrying combination of boy genius and impish brat from the planet Alzarius in E Space.

He was, apparently, brought in to make the fourth Doctor "more fragile" with his "youthful mistakes". Nobody likes a boy genius, and you could kindly call Matthew Waterhouse's acting experience "rudimentary". But the collective hatred of the character among fans has grown and festered into something extraordinary. Here, Adric dies a hero attempting to save his friends, and the freighter crashes into prehistoric Earth in an explosion that would wipe out the dinosaurs and precipitate human life. It's a redemption that grabs a beautiful and touching moment from the jaws of the ridiculous. And it's actually sad. The credits were run over silence at the end.

Behind the sofa

The A-listers had returned, but here was a different kind of Cyberman: bulkier and camper.

The climax of episode three is a great recreation of the classic cliffhanger from Tomb of the Cybermen, but aside from a typically illogical ruse and some references to Mondas, their home planet, these are not really the Cybermen. Writer/script editor Eric Saward says in the DVD extras that he never went in for empty-eyed Cybermen (or indeed, the Daleks) because he found them dull. But his dismissal of their monotone menace, humanity removed, suggests he doesn't quite understand them. The Cyberleader goes off on ponderous two-handers about the nature of emotion, to which the Doctor asks, equally bizarrely, when was the last time he enjoyed a well-prepared meal? These are beings whose terror lies in the fact that they used to be us; physically upgraded and emotionally inhibited until they knew nothing but the urge to enslave. They're not, last time I checked, a race prone to murder by soliloquy.

Sadly, Saward's admission that he wanted the Doctor to be more violent and lose more often suggests the Cybermen were not the only things about the show he didn't understand.

Behind the scenes

Davison remembers how Reid was as baffled by her presence there as most of the audience. He remembered on the DVD extras: "She had absolutely no idea what was going on. She'd turn round after a take and say 'I have no idea what I just said darling!'"

This was the beginning of a campaign by the new producer John Nathan-Turner to fill the show with as many stars of light entertainment as he possibly could: he would go on to cast Ken Dodd and Bonnie Langford in the show. We'll talk more about the controversial Nathan-Turner as we continue through his era – especially in light of the new biography from writer Richard Marson.

Fragments

• We've barely discussed the wonderful Tegan. Janet Fielding served the longest stint (in years, not episodes) of any companion, and while she originated the "gobby-as-main-characteristic" paradigm, she did it with a fabulous panache.

• "I'm just a mouth on legs," she laments before going all Ripley. That phrase has now been adopted by Fielding as her Twitter handle – @jfmouthonlegs – Tegan spent this series trying to return to her job as an air stewardess, and when she finally got there and left, she returned in the very next story. This confusing arc was referenced in this year's The Crimson Horror with the Doctor telling Clara: "I once spent an awful long time getting a gobby Australian back to Heathrow airport." When she asks him why, he doesn't know.

• It's not quite clear why the robotic Cybermen need robotic henchman as well, but good to see they're sticking to their regular tactic of ensnaring a solitary human traitor.

• That flashback through the Cybermen's greatest hits is lovely though.